I was going to ask something similar to this.
If I shoot a Non-Union film while using a few SAG actor friends of mine and it makes it into a big festival, gets picked up for distribution, and SAG takes notice and gets angry, what's my next step? How can I protect my actors? Can I just pay a fee to appease SAG?
An actor who has signed the SAG agreement cannot work on a
non-SAG project. That is the agreement they make with their
Guild. If they break their agreement, a payment later will not
appease the Guild. The agreement isn't "break it now if you
want and pay up later if you need to."
SAG has two low budget agreements specifically for this reason.
I know many filmmakers do not like the contact so they do not
use it. I have never had an issue with it. These actors are your
friends - they know the agreement they have with the Guild. Be
upfront with the actors and allow them to make the decision that
they can live with.
If they do not feel comfortable working outside of their agreement
then contract then you can look into making your movie under one
of their no/low budget agreements.